EP0540306A1 - Elektrischer Kleinmotor - Google Patents

Elektrischer Kleinmotor Download PDF

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Publication number
EP0540306A1
EP0540306A1 EP92309867A EP92309867A EP0540306A1 EP 0540306 A1 EP0540306 A1 EP 0540306A1 EP 92309867 A EP92309867 A EP 92309867A EP 92309867 A EP92309867 A EP 92309867A EP 0540306 A1 EP0540306 A1 EP 0540306A1
Authority
EP
European Patent Office
Prior art keywords
brush
commutator
housing
contact
rotor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP92309867A
Other languages
English (en)
French (fr)
Other versions
EP0540306B1 (de
Inventor
Satoshi Mabuchi Motor Kabushiki Kaisha Nishiwaki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mabuchi Motor Co Ltd
Original Assignee
Mabuchi Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mabuchi Motor Co Ltd filed Critical Mabuchi Motor Co Ltd
Publication of EP0540306A1 publication Critical patent/EP0540306A1/de
Application granted granted Critical
Publication of EP0540306B1 publication Critical patent/EP0540306B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R39/00—Rotary current collectors, distributors or interrupters
    • H01R39/02—Details for dynamo electric machines
    • H01R39/38—Brush holders
    • H01R39/39—Brush holders wherein the brush is fixedly mounted in the holder

Definitions

  • the invention relates to miniature electric motors. Particularly it relates to such motors in which brushes delivering power to the rotor each comprise a plurality of brush pieces which make sliding contact with the commutator.
  • a miniature electric motor of the kind with which this invention is concerned comprises a cylindrical housing with a closed end and a permanent magnet fitted adjacent the inner surface thereof; an end plate closing the other end of the housing; a rotor mounted in bearings in the closed housing end and the end plate for rotation within the housing, the rotor including a commutator, and brushes which make sliding contact with the commutator for the transmission of power thereto.
  • each brush comprises a plurality of brush pieces extending along axes substantially perpendicular to the rotor axis, each brush piece defining a linear contact section for engaging the commutator, which contact sections are inclined relative to one another at predetermined angles such that their natural engagement with the commutator is at circumferentially spaced sections thereof.
  • each brush piece has a V-shaped cross section, the linear contact section being defined by the distal edges of the sides thereof.
  • FIG. 1 A housing 1 is made of a metallic material, such as mild steel, and formed into a cylindrical shape with a closed end.
  • a permanent magnet 2 of an arc-segment shape is fitted to the inner circumferential surface thereof.
  • a rotor comprising an armature 3 facing the permanent magnet 2 and a commutator 4 is rotatably supported in the housing 1.
  • Brushes 7 make sliding contact with the commutator 4, and are electrically connected to input terminals 8.
  • the input terminal 8 is received in an insulating element 10 and protrudes from the end plate 6 for connection to a power source.
  • Bearings 9 are provided in the closed end of the housing 1 and in a bearing retainer 11 formed by a protruding part of the end plate 6 to support a shaft 13 carrying the rotor 5.
  • the brush 7 is fixedly fitted to a brush/terminal mount 8a which is electrically connected to the input terminal 8.
  • the brush 7 has a plurality of brush pieces 7a, 7b and 7c, each of the same shape with its tip bent into a V shape in cross section.
  • the V-shaped tip portions of the brush pieces 7a, 7b and 7c are forced onto the outer circumferential surface of the commutator 4 at an appropriate pressure (brush pressure) by the resiliency of the brush pieces 7a, 7b and 7c, as shown in Figure 3. Since the brush pieces 7a, 7b and 7c are of the same shape, the contact angles ⁇ 0 made by the brush pieces and the outer surface of the commutator 4 are also the same, and the circumferential locations at which the brush pieces make contact with the commutator 4 are likewise substantially identical. Consequently, a groove 4 of the commutator 4 passes the brush pieces 7a, 7b and 7c at the same time. This leads to an abrupt switching of electric current, causing sparks and electrical noises to be generated. These sparks and noises tend to disturb commutated waveforms, resulting in unstable operation of the motor.
  • the brush pieces 7a, 7b and 7c make contact with the commutator along the apex of the V-shaped cross-section of the tips.
  • An alternative is shown in Figure 5 in which the tips are effectively inverted, and contact with the commutator 4 is at the distal edges of the legs of the V-shaped portions of the brush pieces 7a, 7b and 7c.
  • the tips of the brush pieces 7a, 7b and 7c are formed in such a manner that the width of the tips is wider than the width W of the main leg thereof, and each tip has two sides inclined at different angles to the longitudinal axis thereof. It should be noted, however, that the tip of the brush piece 7b has sides parallel with the longitudinal axis; ie, at an angle of zero degrees. The side of the tip of each brush piece 7a and 7c makes an angle of ⁇ 3, in opposite senses, to the longitudinal axis.
  • the inclined angle ⁇ a of the tip shown in Figure 9 can be expressed by the following equation.
  • tan ⁇ a tan ⁇ 3.sin ⁇ 2
  • ⁇ 3 is an inclined angle when the tip shown in Figure 8 is developed
  • ⁇ 2 is the bending angle to form the V shape as shown in Figure 7.
  • the inclined angle ⁇ c of the tip of the brush piece 7c shown in Figure 9 is determined in the same manner.
  • the inclined angle of the brush piece 7b when the tip thereof if considered as the standard angle ⁇ b (not indicated), which in this case is 0 degrees.
  • the inclined angles of the brush pieces 7a and 7c are equal, but opposite, relate to the piece 7b.
  • angles ⁇ a , ⁇ b , and ⁇ c affect directly the positions at which the brushes 7 make sliding contact with the commutator 4. That is, the two edges of the opened legs of the V-shaped portions of the brush pieces 7a, 7b and 7c form tangents to the circumferential surface of the commutator 4.
  • the contact positions are therefore determined by the relation between the angles ⁇ a , ⁇ b , and ⁇ c .
  • angle ⁇ a is determined by the angles ⁇ 3 and ⁇ 2
  • angle ⁇ 2 is common to all the brush pieces 7a, 7b and 7c
  • the angle ⁇ a as a relative angle is determined by the angle ⁇ 3.
  • the angle ⁇ l of the groove 4a may be made larger in some types of miniature motor.
  • the contact angles ⁇ al and ⁇ cl can readily be made larger according to the present invention by increasing the inclined angles ⁇ a and ⁇ c appropriately.
  • contact angles that are sufficiently effective in spark suppression for example, approximately 7 to 25 degrees, can be obtained by changing the inclined angles ⁇ a and ⁇ c .
  • the difference in brush pressure can be kept at negligible or at least low levels, unlike the case shown in Figure 6.
  • the number of brush pieces is not limited to three, as discussed above, and may be any plural number including two, as shown in Figure 11. In this embodiment of the invention, when compared to that of Figures 7 to 10, the central brush piece 7b is omitted.
  • Figure 12 shows the commutated waveform obtained with a miniature motor using the brush 7 as shown in Figures 7 to 10
  • Figure 13 shows the commutated waveform with a miniature motor using the conventional brush for comparison.
  • Figure 13 illustrates that electrical noises are generated frequently, while in Figure 12 there is virtually no electrical noise.
  • Figures 14 and 15 are plots of the relationship between speed and current in a miniature motor; Figure 14 for a motor using a brush according to the invention, and Figure 15 for a motor using a conventional brush.
  • Figure 15 demonstrates unstable running, with speed reducing with the lapse of time, while Figure 14 shows a substantially constant running speed at around 5,000 rpm.
  • Figure 15 shows that there were considerable fluctuations, with noise increasing with the lapse of time, while Figure 14 indicates little noise or changes thereof over time.
  • this invention makes it possible to suppress spark generation and stabilize commutated waveforms and revolution in a miniature motor in which a plurality of brush pieces make contact with the commutator.
  • Each brush piece passes the grooves of the commutator at different times as a consequence of the different inclined angles of the tips to the brush pieces.
  • the tangential lines at the points at which the tips of the brush pieces make contact with the commutator are inclined to each other.

Landscapes

  • Motor Or Generator Current Collectors (AREA)
  • Dc Machiner (AREA)
  • Motor Or Generator Frames (AREA)
EP92309867A 1991-10-30 1992-10-28 Elektrischer Kleinmotor Expired - Lifetime EP0540306B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP88835/91 1991-10-30
JP1991088835U JP2579723Y2 (ja) 1991-10-30 1991-10-30 小型モータ

Publications (2)

Publication Number Publication Date
EP0540306A1 true EP0540306A1 (de) 1993-05-05
EP0540306B1 EP0540306B1 (de) 1996-04-03

Family

ID=13954011

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92309867A Expired - Lifetime EP0540306B1 (de) 1991-10-30 1992-10-28 Elektrischer Kleinmotor

Country Status (4)

Country Link
US (1) US5296774A (de)
EP (1) EP0540306B1 (de)
JP (1) JP2579723Y2 (de)
DE (1) DE69209617T2 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003028190A1 (de) * 2001-09-21 2003-04-03 Robert Bosch Gmbh Kommutierungsvorrichtung für eine elektrische maschine
CN109599975A (zh) * 2018-04-24 2019-04-09 东风汽车电气有限公司 一种起动机

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5485049A (en) * 1994-05-25 1996-01-16 United Technologies Motor Systems, Inc. Multi-speed motor
WO1996041410A1 (en) * 1995-06-07 1996-12-19 Itt Automotive Electrical Systems, Inc. Reduced speed growth in windshield wiper motor
US6734594B2 (en) * 2001-09-10 2004-05-11 Samsung Electro-Mechanics Co., Ltd. Vibration motor
US9172196B2 (en) * 2012-07-31 2015-10-27 Omron Corporation Brush having a plurality of elastic contact pieces arranged in parallel
CN211404958U (zh) * 2019-11-21 2020-09-01 广东德昌电机有限公司 有刷电机及其电刷结构

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2172446A (en) * 1985-03-12 1986-09-17 Mabuchi Motor Co Brush gear for electric motors
GB2203899A (en) * 1987-03-16 1988-10-26 Mabuchi Motor Co Brush shoe cross section for a cranked commutator

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3191084A (en) * 1961-11-22 1965-06-22 Hitachi Ltd Current collector assembly for small d. c. motors
JPS5121802U (de) * 1974-08-06 1976-02-18
JPS5298906A (en) * 1976-02-14 1977-08-19 Matsushita Electric Works Ltd Commutator apparatus
JPS54137606A (en) * 1978-04-18 1979-10-25 Mabuchi Motor Co Small motor
US4358699A (en) * 1980-06-05 1982-11-09 The University Of Virginia Alumni Patents Foundation Versatile electrical fiber brush and method of making
JPS5866865U (ja) * 1981-10-28 1983-05-07 マブチモ−タ−株式会社 小型モ−タ
JPH0448140Y2 (de) * 1986-01-09 1992-11-12

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2172446A (en) * 1985-03-12 1986-09-17 Mabuchi Motor Co Brush gear for electric motors
GB2203899A (en) * 1987-03-16 1988-10-26 Mabuchi Motor Co Brush shoe cross section for a cranked commutator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 9, no. 143 (E-322)(1866) 18 June 1985 & JP-A-60 26 435 ( MATSUSHITA DENKI SANGYO KK ) 9 February 1985 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003028190A1 (de) * 2001-09-21 2003-04-03 Robert Bosch Gmbh Kommutierungsvorrichtung für eine elektrische maschine
CN109599975A (zh) * 2018-04-24 2019-04-09 东风汽车电气有限公司 一种起动机
CN109599975B (zh) * 2018-04-24 2024-04-19 东风电驱动系统有限公司 一种起动机

Also Published As

Publication number Publication date
JP2579723Y2 (ja) 1998-08-27
DE69209617D1 (de) 1996-05-09
EP0540306B1 (de) 1996-04-03
US5296774A (en) 1994-03-22
JPH0541383U (ja) 1993-06-01
DE69209617T2 (de) 1996-08-22

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